Conventionally, bis(aminomethyl)cyclohexanes are well known for a polyamide material used for fibers and films.
Furthermore, bis(isocyanatomethyl)cyclohexane derived from bis(aminomethyl)cyclohexane is useful for a polyurethane material used for, for example, paints, adhesives, and plastic lenses, and a polyisocyanate composition material used for, for example, a curing agent for paints.
The bis(aminomethyl)cyclohexane includes two stereoisomers of trans-bis(aminomethyl)cyclohexane (hereinafter may be referred to as trans isomer) and cis-bis(aminomethyl)cyclohexane (hereinafter may be referred to as cis isomer), and it has been known that the ratios of the cis isomer and the trans isomer in bis(aminomethyl)cyclohexane affect various physical properties of polyamides and polyurethanes produced by using the bis(aminomethyl)cyclohexane.
For example, in polyamides, a higher trans isomer ratio in bis(aminomethyl)cyclohexane, i.e., the material for polyamides, improves physical properties such as a melting point and thermal stability, and a polyamide that is suitable for fibers and films can be produced.
In polyurethanes, using bis(isocyanatomethyl)cyclohexane derived from bis(aminomethyl)cyclohexane having a high trans isomer ratio as the material for polyurethane allows for production of polyurethane having excellent heat resistance and solubility to solvents.
Therefore, a production method for bis(aminomethyl)cyclohexane having a high trans isomer ratio is desired in various industrial fields.
As a method for producing bis(aminomethyl)cyclohexane having a high trans isomer ratio, the following method for producing trans-1,4-bis(aminomethyl)cyclohexane is proposed: for example, hydrogenerated terephthalic acid or its derivative is allowed to contact with ammonia, trans-1,4-dicyanocyclohexane is taken out from the produced 1,4-dicyanocyclohexane by crystallization using an aqueous solvent, and thereafter, the produced trans-1,4-dicyanocyclohexane is allowed to contact with hydrogen. Furthermore. Patent Document 1 has proposed the following: after taking out trans-1,4-dicyanocyclohexane by crystallization, the remaining cis-1,4-dicyanocyclohexane is allowed to contact with ammonia again with hydrogenerated terephthalic acid or its derivative for isomerization.
Meanwhile, because crystallization is generally troublesome, when producing trans-bis(aminomethyl)cyclohexane industrially, as described in Patent Document 1, taking out trans-1,4-dicyanocyclohexane by crystallization may cause the process to be complicated. Thus, for simplifying the process, for example, it has also been examined to take out trans-1,4-dicyanocyclohexane from 1,4-dicyanocyclohexane (mixture of cis isomer and trans isomer) by distillation.